The connection between exercise and blood sugar levels

Experts agree the best way to effectively manage your diabetes is a combination of good lifestyle choices—notably, diet and exercise.

By exercise, they mean a blend of aerobic activity, strength-building exercise and flexibility training. And in fact, a combination of strength-training and aerobic exercise seems to be more effective for keeping your blood sugar levels under control than either type of activity by itself.

However, you can’t just lace up your sneakers and start pounding the pavement or hoisting the dumbbells. You have to prepare for the effect that exercise has on your blood glucose levels—namely, it tends to lower your blood glucose levels. The specific amount will depend on how long you’re active.

Follow these steps to stay on top of your blood sugar levels while you’re getting your sweat on:

Talk to your doctor and healthcare team

Before you do anything, check with your doctor and get screened for any underlying complications or anything that might predispose you to certain types of injuries, like severe peripheral neuropathy and retinopathy. They can help you develop a plan and set a target range for your blood glucose levels, too.

Eat before exercising

Break the fast! Don’t put off eating so you can exercise first. Eating a couple of hours prior to a workout can help you keep your blood sugar level at a normal level.

Test your blood sugar levels

It’s crucial to have a good handle on your specific blood glucose levels before, during and after you exercise. So, before you work out, test to make sure your blood glucose is less than 250 mg/dl, as the 100-250 mg/dl is generally considered a safe zone. If your blood glucose exceeds the 250 mg/dl mark, test your urine for ketones. If ketones are present, it’s best to postpone your workout until there aren’t any ketones. And if your blood glucose exceeds 300 mg/dl, wait until the level drops to a safer level before you work out.

Write it down

So you’ve tested your blood glucose levels. Now it’s time to record them. The National Diabetes Information Clearinghouse suggests writing down in a journal your blood sugar levels and the length of time you spend exercising to help you track how your activity affects your blood glucose. Another option: Use a smartphone app like Diabetes Buddy, TRACK3 or LogFrog. Over time, you can see patterns developing, which will help you be proactive.

Be prepared for hypoglycemia

If your blood glucose levels dip below 70 dg/ml, you might experience shakiness, dizziness, a rapid heartbeat, confusion, fatigue or some combination of these symptoms. Hypoglycemia tends to be more of a problem for people with type 1 diabetes than for people with type 2 diabetes, except for people who take insulin or an insulin secretagogue, according to the American Diabetes Association. It’s worthwhile to be prepared, though, just in case. Bring along a snack containing carbs, juice or glucose tablets in addition to your blood glucose testing supplies. Your muscles keep on burning glucose even after you stop exercising, so keep your eye out for possible signs of hypoglycemia for the next 24 hours.

Hydrate, hydrate, hydrate

Drink plenty of water—and not just during your workout. Guzzle 17 ounces (approximately two cups) about two hours before you exercise. Since you’re going to lose fluids when you sweat, you’ll also need to keep on drinking water, especially if it’s really warm outside.